1. Field of the Invention
The present invention relates to liquid crystal devices, projection display devices, and manufacturing methods for substrates for liquid crystal devices. This invention particularly relates to the construction of desirable liquid crystal devices to be used as a light source for a liquid crystal projector, and to a manufacturing method for a substrate for a liquid crystal device.
2. Description of Related Art
For a projection liquid crystal display device, such as a liquid crystal projector, there is the three-panel type in which three liquid crystal panels corresponding to the three primary colors red (R), green (G), and blue (B) are used, and the one-panel type in which one liquid crystal panel and a color generating device are used. For a liquid crystal light source which is a part of such a projection liquid crystal display device, active matrix type liquid crystal panels are typically used.
Also, a liquid crystal panel comprises, for example an active matrix type liquid crystal light source and polarizing plates which are disposed in the front and in the rear of the active matrix type liquid crystal light source. FIG. 18 is a cross section showing an example of the construction of such a conventional liquid crystal light source.
A liquid crystal light source is made such that liquid crystal is enclosed between two transparent substrates as shown in FIG. 18. The liquid crystal light valve is provided with a thin film transistor (hereinafter called TFTs) array substrate 10 and facing substrate 20 which is disposed to face the TFT array substrate.
On the TFT array substrate 10, a plurality of scanning lines 3a and a plurality of data line 6a are disposed so as to cross like in a lattice. A pixel switching TFT 30 is disposed corresponding to the cross points of the scanning lines 3a and the data lines 6a. The scanning lines 3a cross over a semiconductor layer la of the TFT 30 via insulating thin layer 2, and channel area 1axe2x80x2 is formed in a crossing area of the semiconductor layer 1a. A data line 6a crossing over the scanning line 3a is connected electrically to a source area 1d of the semiconductor layer 1a via contact hole 5. Also, pixel electrode 9a is formed in an area which is surrounded by the scanning lines 3a and the data lines 6a on an upper layer of the data line 6a. The pixel electrode 9a is connected electrically to a drain area 1e of the semiconductor layer 1a via the contact hole 8. An alignment layer 16 subjected to an alignment layer treatment by a rubbing treatment is formed on the pixel electrode 9a. The alignment layer 16 is formed by an organic layer of polyimide.
In such a TFT array substrate 10, as compared to the area on which the pixel electrode 9a is formed, the thickness of the area in which TFT 30 is a non-pixel area, the thickness of the area in which the scanning line 3a is formed, and the thickness of the area in which data line 6a is formed tends to be large because the insulating layers 4 and 7 for such areas and the wiring are layered therein; thus, the gap section is formed on the surface of the alignment layer 16. The gap is particularly large between the area where the TFT 30 is formed and the area where the pixel electrode 9a is formed. Furthermore, if a first shading layer 11a is formed under TFT 30 so as to shield a capacity line 3b and TFT 30 for higher quality display, the gap section tends to be reality visible.
Recently, more finely pitched pixels tend to be desired according to the requirements for size reduction of the liquid crystal light source in view of greater fineness and greater brightness of the liquid crystal projector. However, for example, if the pixel pitch becomes as fine as 20 xcexcm, there will be areas where effective rubbing treatment on the alignment layer is impossible because of the gap section on the underlayer of the alignment layer in the case of liquid crystal light valve in which an alignment layer made of an organic layer such as polyimide is provided; thus, disclination of the liquid crystal occurs nearby sometimes degrading display quality. Such a problem becomes more apparent if the pixel pitch is made finer.
Also, the intensity of the light incident on the light valve has increased for brighter liquid crystal projectors. Because of this, the alignment layer made of an organic layer such as of polyimide deteriorates due to light and heat, and alignment uniformity of the alignment layer decreases. Thus, the orientation of the liquid crystal molecules lose uniformity, the contrast of the display decreases, and sometimes ultimately leads to inferior display quality. The reasons such problems occur is that the organic layer made of polyimide absorbs some amount of the 400 to 450 nm wavelength visible light, the alignment layer deteriorates due to the absorption of the light, the orientations of the liquid crystal lose alignment uniformity near the deteriorated area of the alignment layer, and thus degraded display quality results.
In order to solve such problems, a light source has been provided in which the alignment layer is made of a layer obtained by oblique evaporation of inorganic material such silicon oxide (SiO) instead of an organic layer such as polyimide, and in such a way that the liquid crystal molecules are oriented unidirectionally by the surface forming effect of the inorganic oblique evaporation layer. The alignment layer made of an inorganic oblique evaporation layer can be formed by unidirectionally vacuum-evaporating the inorganic material onto a substrate fixed at a certain angle, more specifically from a direction slanted by 10 to 30 degrees to the substrate so as to grow the columnar structure of the inorganic material disposed at a predetermined angle to the substrate, and such a method is called a oblique evaporation method. The alignment layer obtained in this way has advantages such as superior light resistance and heat-resistance as compared to the alignment layer made of an organic material such as polyimide due to its inorganic layer construction, superior durability of the liquid crystal light valve, and loss of alignment uniformity of the liquid crystal caused by incorrect rubbing treatment seen in the case of the organic layer such as one of polyimide, even if the pixel pitch is made finer.
However in contrast to advantages such as light resistance and heat resistance, an alignment layer made of an inorganic layer has disadvantages such as weak alignment uniformity of liquid crystals as compared to an alignment layer made of an organic layer. Accordingly, in a liquid crystal device using an inorganic alignment layer, disclination easily occurs if any factor occurs causing loss of alignment uniformity of the liquid crystals; inferior display is provided. Specifically, surfaces of the active matrix substrate forming the liquid crystal light valve become irregular when forming switching elements such as TFTs, signal lines such as data lines and scanning lines, and pixel electrodes on the active matrix substrate. Such irregularities in the surfaces produce shadows on the substrate during oblique evaporation; thus, defective parts may sometimes be generated on the alignment layer. In the case in which there are such defects on the alignment layer, the organic layer may be able to compensate for the defect by its own sufficient aligning uniformity. However, the aligning uniformity of the inorganic evaporation layer is so weak that disclination may be caused. Because of this tendency, inferior display such as one in which there is light leakage in the domain in which the alignment direction is different occurs, and the display quality decreases due to low contrast.
As a solution for reducing the disclination, there is a method called a pre-tilt method in which the liquid crystal molecules are disposed slant to the surface of the substrate in advance when no voltage is impressed. Generally, the disclination can be progressively reduced as the pre-tilt angle increases. However, if the pre-tilt angle is increased in the case of an inorganic alignment layer in which the aligning uniformity was originally weak, the spiral structure of the liquid crystals between the substrates becomes unstable. Therefore, inferior display is produced due to the existence of reverse twist domains which are areas in which the twisting directions of liquid crystals becomes partially opposite.
This problem also occurs in liquid crystal devices using alignment layers made of an inorganic oblique evaporation layer formed on the underlayer on which surface the gap section exists.
Above problem is not limited to the case of an active matrix type liquid crystal device using a 3-terminal-type-element such as a TFT element; but it is a common problem among active matrix type liquid crystal devices using 2-terminal-type-elements such as a Thin-Film-Diode (hereinafter called TFD) and passive matrix type liquid crystal devices whenever an inorganic alignment layer is used in the liquid crystal device.
This invention was made in consideration of solving the above problems, and an object of the invention is to minimize the inferior alignment of liquid crystals in the liquid crystal device using an inorganic alignment layer in which alignment uniformity is poor, and to provide a liquid crystal device which can prevent inferior display and low contrast due to the inferior alignment, and also to provide a projection display device in which display quality is high by using the above liquid crystal device.
Also, an object of this invention is to provide a liquid crystal device by which inferior evaporation areas of inorganic materials is not generated near the gap section of the underlayer of the alignment layer even if pixel elements are as fine as 20 xcexcm or less, to prevent the occurrence of inferior alignment of the liquid crystals due to the irregularities in the alignment layer due to inferior evaporation areas of inorganic material, and to reduce the occurrence of inferior display. A manufacturing method for a substrate for such a liquid crystal device is another object of the present invention.
In order to achieve the above objects, a liquid crystal device of this invention is characterized in that a liquid crystal layer (50) is disposed between a pair of substrates (20) facing each other, inorganic alignment layers (36, 42) are disposed on a surface of a liquid crystal layer side of the pair of the substrates, average pre-tilt angle xcex8 of liquid crystal molecule 50a of the liquid crystal layer is 5 degreesxe2x89xa6xcex8xe2x89xa620 degrees, twist angle xcfx86 of the liquid crystal molecule (50a) of the liquid crystal layer, cell gap d, and helical pitch P of the liquid crystal molecule of the liquid crystal layer satisfy the Relationship R1 of (0.6/360)xcfx86 less than d/P less than (1.4/360)xcfx86.
Also, a liquid crystal device of the present invention is characterized in that a liquid crystal layer (50) is disposed between a pair of substrates (20) facing each other, inorganic alignment layers (36, 42) are disposed on a surface of a liquid crystal layer side of the pair of the substrates, average pre-tilt angle xcex8 of liquid crystal molecule 50a of the liquid crystal layer is xcex8 greater than 20 degrees, twist angle xcfx86 of the liquid crystal molecule (50a) of the liquid crystal layer, cell gap d, and helical pitch P of the liquid crystal molecule of the liquid crystal layer satisfy the Relationship RELATIONSHIP 2 of (0.8/360)xcfx86 less than d/P less than (1.6/360)xcfx86.
In order to avoid inferior alignment caused by the weak alignment uniformity of the inorganic alignment layer in a liquid crystal device using the inorganic alignment layer, the inventors examined a feature of the liquid crystal material such as the xe2x80x9chelical pitchxe2x80x9d after various experiments and research, and they discovered that inferior alignment can be prevented in the liquid crystal device which uses an inorganic alignment layer by setting the ratio between the cell gap of the liquid crystal device and the helical pitch of the liquid crystal layer in a predetermined range of values. By doing this, a liquid crystal device can be realized with no inferior display characteristics such as light leakage due to disclination and reduced contrast. The helical pitch being described here is the length of the liquid crystal layer corresponding to 360 degrees of unidirectional rotation of the major axis of liquid crystal molecules in a liquid crystal layer under conditions that the alignment uniformity is not given. Reasons for determining the range of d/P ratio between cell gap d and helical pitch P is explained with reference to experimental results.
According to data from experiments by the inventors of the present invention, as mentioned above, the d/P ratio between cell gap d and helical pitch P can be generalized in two different formulae such as the above Relationships RELATIONSHIP 1 and RELATIONSHIP 2 according to the two different ranges of the average pre-tilt angle xcex8 of liquid crystal molecules in a liquid crystal layer such as 5 degreesxe2x89xa6xcex8xe2x89xa620 degrees and xcex8 greater than 20 degrees. In the case of the inorganic alignment layer, the columnar structure which forms the alignment layer sometimes becomes uneven corresponding to a factor such as the surface shape of the substrate when forming the alignment layer, particularly in an oblique evaporation method. Thus, according to such conditions, a phrase such as xe2x80x9caverage pre-tilt anglexe2x80x9d is used herein because it is anticipates that the pre-tilt angle will differ according to the position on the substrate, and RELATIONSHIP 1 and RELATIONSHIP 2 may preferably be selected according to the pre-tilt angle which is determined as an average tilt-angle of the entire substrate.
In order to control the pre-tilt angle on an inorganic alignment layer, various methods can be employed. Typically, a pre-tilt angle of 5 degreesxe2x89xa6xcex8xe2x89xa620 degrees can be obtained relatively easily with the forming method of the alignment layer by forming an inorganic evaporation layer by evaporation of inorganic material onto the substrate unidirectionally, by evaporating in a vacuum condition for a second time from a different angle inside the substrate, and by forming another inorganic evaporation layer on the inorganic evaporation layer. In order to describe a structure of the alignment layer, the inclination direction of the columnar structure of an inorganic material which is made of two layers of an oblique evaporation layer having a columnar structure of inorganic material slanting in one direction to form both oblique evaporation layers can realize a pre-tilt angle such as 5 degreesxe2x89xa6xcex8xe2x89xa620 degrees as long as it is an alignment layer in which azimuth angle directions inside the substrate plane are different.
Also, in contrast to the above evaporations performed twice, a pre-tilt angle such as xcex8 greater than 20 degrees can be relatively easily obtained if the alignment layer is formed once by evaporation. In order to describe a structure of the alignment layer, a pre-tilt angle such as xcex8 greater than 20 degrees can be realized as long as the alignment layer is made of a columnar structure of an oblique evaporation layer made of inorganic material slanting unidirectionally.
For specific materials for the inorganic alignment layer, silicon oxide (SiO), Titanium oxide (TiO2), Magnesium fluoride (MgF) can be used, and SiO is used most commonly.
A projection display device of the present invention is provided with any of the liquid crystal devices of the present invention, and a projection display device of the present invention is characterized in comprising a light source, the liquid crystal device which modulates the light emitted from the light source and a magnifying projection optical system which magnifies the light modulated by the liquid crystal device and projects the light onto a projection screen.
According to this construction, by using a liquid crystal device of the present invention, a projection display device with no low contrast due to inferior alignment of the liquid crystal can be realized with a high quality display.
Also, various experiments have been performed and the result of the experiments have been evaluated by the inventors of the present invention so as to prevent the occurrence or inferior alignment layer due to a defective area of evaporation of inorganic material generated in or near the gap section of the underlayer of alignment layer formed by an inorganic oblique evaporation layer. The reason is that the evaporation is hardly possible in the area shaded by the gap section on the surface of the underlayer of the alignment layer; thus, such area becomes a evaporation defect area when an element substrate on which a plurality of wiring and a plurality of insulating layers are formed is fixed at a certain angle and then forming an alignment layer by unidirectional evaporation of an inorganic material.
Furthermore, after the various experiments and the evaluation of the result of the experiments, the inventors of the present invention discovered that it is desirable to alter the azimuth angle direction of the oblique evaporation of which the direction is at least along the surface inside the surface of the substrate when the underlayer of the inorganic alignment layer made of an inorganic oblique evaporation layer formed on the substrate has the gap section on the surface of the substrate, and to perform the oblique evaporation two or more times. In more detail, the inventors discovered a method such as forming the first inorganic oblique evaporation layer by the oblique evaporation of inorganic material unidirectionally onto the substrate on which surface the underlayer having the gap section is formed, and forming the second inorganic oblique evaporation layer in an area close to the gap section and on the first inorganic oblique evaporation layer by the oblique evaporation of inorganic material from a direction in which the azimuth angle direction inside the plane of the substrate is at least different from the direction of the oblique evaporation of inorganic material in the forming step of the first oblique evaporation layer. According to this method, the first and the second inorganic oblique evaporation layers are formed by the columnar structure of the slant inorganic material. The slanting direction of the columnar structure of inorganic material which forms the first inorganic oblique evaporation layer, and the slanting direction of the columnar structure of inorganic material which forms the second inorganic oblique evaporation layer are different in that the azimuth angle directions along the direction inside the surface of the substrate are different. In a liquid crystal device in which the inorganic alignment layer having such first and second inorganic oblique evaporation layers are formed, the above problems are solved.
In addition, in the case of forming an alignment layer for a liquid crystal panel by an oblique evaporation layer made of SiO, the method in which the oblique evaporation is performed twice is known from the disclosure in IEEE Trans. Electron. Devices, Vol. ED-24(7), 805(1977) by M. R. Johnson and P. A. Penz. However, the liquid crystal device of this disclosure is a single matrix type direct-view liquid crystal panel. This liquid crystal device is not as small as a liquid crystal device for a projection light source in a liquid crystal projector of this invention, and this liquid crystal device is not an active matrix type liquid crystal panel in which the pixel pitch of pixel electrodes is as fine as 20 xcexcm and the underlayer of the alignment layer has a gap section due to the scanning lines and the data lines.
Also, an object of performing the oblique evaporation twice in the above conventional art was to make the pre-tilt angle of the liquid crystal molecules less than 20 degreesin a simple matrix type direct-view liquid crystal panel. Thus, in the case in which the gap on the surface of the underlayer of the inorganic alignment layer is large, preventing the occurrence of defect evaporation areas of inorganic material in areas close to the gap section was not treated previously.
In order to achieve the above objects, in a liquid crystal device of present invention, a liquid crystal layer is disposed between a pair of substrates facing each other; inorganic alignment layers are disposed on a surface of a liquid crystal layer side of the pair of the substrates, and an underlayer of at least one of the inorganic alignment layers have a gap section. Additionally, the inorganic alignment layers formed on the underlayer having the gap section comprise a first inorganic oblique evaporation layer and a second inorganic oblique evaporation layer formed in an area close the gap section and on the first inorganic oblique evaporation layer. The first and the second inorganic oblique evaporation layers are made of slanted columnar structures of inorganic material. Azimuth angle directions of the slanting direction of the columnar structure of an inorganic material forming both the first and the second oblique evaporation layers are different inside the plane of the substrate.
According to the liquid crystal device with such a construction, inorganic alignment layers formed on the underlayer having the above gap section comprises the first inorganic oblique evaporation layer formed by a columnar structure of slant inorganic material and the second inorganic oblique evaporation layer, and the slant direction of inclination of the columnar structure of inorganic material of the second inorganic oblique evaporation layer is different from the slant direction of the columnar structure of the first inorganic oblique evaporation layer, at least with regard to the azimuth angle direction. Also, because the second inorganic oblique evaporation layer is formed in an area close to the above gap section, even if a pixel pitch as fine as 20 xcexcm or less is formed, the occurrence of uneven evaporation of inorganic material or insufficient evaporation in areas close to the above gap section can be reduced. Accordingly, even if the pixel pitch is as fine as 20 xcexcm or less, the inorganic alignment layer formed on the underlayer having a gap section on the surface of underlayer can be free from defects, the defective alignment of liquid crystals due to a defective alignment layer can be prevented, and the occurrence of defective display, such as lowered contrast, can be prevented. Such effects can also be obtained even if the pixel pitch is as fine as 15 xcexcm or less.
Also, in a liquid crystal device in this invention, a liquid crystal layer is disposed between a pair of substrates facing each other, a plurality of pixel electrode is disposed in a matrix, a plurality of switching devices which drive the plurality of the pixel electrodes, and a plurality of data lines and a plurality of scanning lines connected respectively to the plurality of the switching devices are provided on either one of the two substrates. Facing electrodes are provided on the other substrate, inorganic alignment layers are provided respectively on the surface of the liquid crystal side of the two substrates, and an underlayer of at least one of the inorganic alignment layer on the side of which the switching device is provided has a gap section on its surface. Inorganic alignment layers formed on the underlayer having gap sections comprising a first inorganic oblique evaporation layer and a second inorganic oblique evaporation layer formed in an area close to the gap section and on the first inorganic oblique evaporation layer. The first and the second inorganic oblique evaporation layers are made of an slant columnar structure of inorganic material. Azimuth angle directions of the direction of inclination of the columnar structure of inorganic material constructing both the first and the second oblique evaporation layers are different along the inside plane direction of the substrate.
In such a liquid crystal device, an inorganic alignment layer formed on the underlayer having the above gap section comprises the first inorganic oblique evaporation layer formed by a columnar structure of slant inorganic material and the second inorganic oblique evaporation layer, and the direction of inclination of the columnar structure of the inorganic material of the second inorganic oblique evaporation layer is different from the direction of inclination of the columnar structure of the first inorganic oblique evaporation layer at least with regard to the azimuth angle direction. Additionally, because this second inorganic oblique evaporation layer is formed in an area close to the above gap section, the occurrence of uneven evaporation of inorganic material or insufficient evaporation in areas close to the above gap section can be reduced. Accordingly, even if the pixel pitch is as fine as 20 xcexcm or less, an inorganic alignment layer formed on the underlayer having a gap section on the surface of the underlayer can be free from defects, the defective alignment of liquid crystals due to the defective alignment layer can be prevented, and the occurrence of defective display, such as lowered contrast can be prevented. Such effects can also be obtained even if the pixel pitch is as fine as 15 xcexcm or less.
In addition, in this invention, components on the substrate on which switching devices are provided for constructing the pixels are scanning lines (gates) and data lines, the switching devices connected to these lines, pixel electrode, and supplementary capacity (accumulation capacity) and the like. On the substrate on which the facing electrodes are provided, constituting parts of pixels are shading layers (black matrix), facing electrodes and the like. Pixel pitch is, for example, the pixel electrode pitch or the like.
Also, in a liquid crystal device with any structure of present invention, the inclination direction of a columnar structure of an inorganic material forming the above first inorganic oblique evaporation layer and the direction of the inclination of the columnar structure of the inorganic material forming the above second inorganic oblique evaporation layer can differ by 90 degrees with regard to the azimuth angle direction. In the case of an ordinary active matrix type liquid crystal device, data lines and scanning lines are crossing in nearly an orthogonal manner such as in a matrix, and an alignment layer can be disposed securely in an area close to gap sections crossing each other by twice performing evaporation from the direction of which azimuth angle direction differs by 90 degrees.
Also, in a liquid crystal device with any structure of the present invention, the thickness of the first inorganic oblique evaporation layer should preferably be 5 nm to 16 nm, and the thickness of the second inorganic oblique evaporation layer should preferably be 10 nm to 40 nm.
If the thickness of the first inorganic oblique evaporation layer is less than 5 nm, the pre-tilt angle is not arranged for the liquid crystal molecule, and such a condition may cause disclination. If the thickness is larger than 16 nm, the effect which should be obtained by the second inorganic oblique evaporation layer cannot be obtained sufficiently; thus, the pre-tilt angle of liquid crystal molecules becomes larger than 20 degrees.
If the thickness of the second inorganic oblique evaporation layer is less than 10 nm, the effect that the columnar structure of this second inorganic oblique evaporation layer fills the gap of the columnar structure of inorganic material forming the first inorganic oblique evaporation layer is insufficient; thus the pre-tilt angle of the liquid crystal molecules becomes larger than 20 degrees. If the thickness of the second inorganic oblique evaporation layer is larger than 40 nm, the gap of the columnar structure of the inorganic material forming the first inorganic oblique evaporation layer is filled; thus, the pre-tilt angle is not disposed on the liquid crystal molecule, and therefore there is no pre-tilt in alignment.
Also, in a liquid crystal device with any construction of the present invention, the average pre-tilt angle of the liquid crystals of the above liquid crystal layer should preferably be 5 degrees to 15 degrees.
Also, in a liquid crystal device with any construction of the present invention, an oblique evaporation layer made of silicon oxide can be used for the above inorganic alignment layer.
In the manufacturing method for the substrate a for liquid crystal device by oblique evaporation of inorganic material on an underlayer having a gap section on the surface formed on the substrate so as to form the inorganic alignment layers, a manufacturing method for a substrate for a liquid crystal device of the present invention is characterized in comprising a first oblique evaporation step by unidirectional oblique evaporation of the inorganic material on the substrate on which the underlayer having the gap section is formed on the surface of the substrate so as to form the first inorganic oblique evaporation layer, a second oblique evaporation step by oblique evaporation of inorganic material from at least a different azimuth angle inside the substrate from the oblique evaporation direction of the inorganic material in the first oblique evaporation step so as to form the second oblique evaporation layer in an area close to the gap section and on the first inorganic oblique evaporation layer.
According to such a manufacturing method for a substrate for a liquid crystal device, the first and the second oblique evaporation steps are arranged, the oblique evaporation direction of the inorganic material in the first oblique evaporation step and the oblique evaporation direction of inorganic material in the second oblique evaporation step are different with regard to at least the azimuth angle direction along an inside surface direction of the substrate. Therefore, even if there is such an area in which inorganic material is not vacuum deposited in the first oblique evaporation step, inorganic material can be vacuum deposited to such area in the second oblique evaporation step. In the first oblique evaporation step, an area close to the gap section may be in the shadow; thus, there may be an area in which the first inorganic oblique evaporation layer is not formed. In the second oblique evaporation step, by performing the oblique evaporation of inorganic material at a different azimuth angle direction from the azimuth angle direction employed in the first oblique evaporation step, the second inorganic oblique evaporation layer can be formed by performing the evaporation of inorganic material onto the area where an inorganic oblique evaporation layer is not formed due to the shadow by the gap section in the first oblique evaporation step. Also, in this second oblique evaporation step, the second inorganic oblique evaporation layer is formed not only in an are close to the gap section, but also on the first inorganic oblique evaporation layer on at least both sides of the gap section. According to the manufacturing method for a substrate for a liquid crystal device with such a construction, a substrate for a liquid crystal device which can be provided for a liquid crystal device with any construction of the present invention can be manufactured.
Also, in the manufacturing method for a substrate for a liquid crystal device with the above construction in the present invention, the first inorganic oblique evaporation layer can be preferably formed, the second inorganic oblique evaporation layer can be preferably formed in an area close to the gap section and on the first inorganic oblique evaporation layer; thus, the direction of oblique evaporation of inorganic material in the first oblique evaporation step and the direction of oblique evaporation of inorganic material in the second oblique evaporation step should preferably differ by approximately or exactly 90 degrees with regard to the azimuth angle direction. In the case of an ordinary active matrix type liquid crystal device, data lines and scanning lines cross nearly orthogonally in a matrix; thus, an alignment layer can be reliably formed in an area close to each gap section crossing each other by performing evaporation twice from different azimuth angle directions.
Also, in a manufacturing method for a substrate for a liquid crystal device with any construction of the present invention, deposition angle of inorganic material of the first oblique evaporation from the substrate should preferably be 5 degrees to 10 degrees, and the deposition angle of inorganic material of the second oblique evaporation from the substrate should preferably be 25 degrees to 30 degrees.
If the deposition angle of the oblique evaporation direction in the first oblique evaporation from the substrate is less than 5 degrees, the density of the columnar structure formed is too low; thus the alignment direction of the liquid crystal molecules becomes unstable, and the alignment uniformity inside the plane along the inside plane direction of the substrate is lost.
If the deposition angle of oblique evaporation direction from the substrate is larger than 10 degrees, the density of the columnar structure formed becomes high, and the effect that the gap of the columnar structure of the first inorganic oblique evaporation layer is filled by the columnar structure of the second inorganic oblique evaporation layer can hardly be obtained; thus, as a result, the area where there is no pre-tilt in the alignment of liquid crystal molecule expands when manufacturing the liquid crystal device with this substrate.
If the deposition angle of oblique evaporation direction from the substrate in the second oblique evaporation step is less than 25 degrees, the effect that the gap of the columnar structure of the first inorganic oblique evaporation layer is filled by the columnar structure of the second inorganic oblique evaporation layer can hardly be obtained. If the deposition angle of the oblique evaporation from the substrate is larger than 30 degrees, anisotropy in the formed layer is lost; thus, the function of aligning the liquid crystal molecule is lost.
Also, in a manufacturing method for a substrate for a liquid crystal device with any construction of the present invention, in either one of the first oblique evaporation step or the second oblique evaporation step, the oblique evaporation direction should preferably be selected according to the construction and the disposition of the gap section formed on the surface of the underlayer in that the effect that the inorganic oblique evaporation layer can be formed separately by performing the oblique evaporation twice can be enhanced in the oblique evaporation of the inorganic material. For example, in a case in which there are high gap sections and low gap sections on the surface of the underlayer, oblique evaporation of inorganic material should preferably be performed from the direction of the low gap section in the first oblique evaporation step, and oblique evaporation of inorganic material should preferably be performed from a direction such that the azimuth angle direction along the inside plane direction of the substrate is at least different from the oblique evaporation direction of inorganic material in the first oblique evaporation step in the second oblique evaporation step. As mentioned above, the first oblique evaporation step is performed on the surface of the substrate at a narrow angle, and the second oblique evaporation step is performed on the surface of the substrate at a wide angle. In such a case, the shaded part which is a shadow in the first oblique evaporation step, such as no-inorganic-layer area, becomes small; thus, the alignment layer is formed more reliably.
Also, the reason the oblique evaporation should be performed according to above method is understandable according to following.
As shown in FIG. 16, the Relationship among xcex8 as an evaporation angle of silicon oxide, xcex94Z as a height of the gap between wiring 9c and surface of substrate 10a, xcex94L as a width of a non-alignment-layer area where an inorganic oblique evaporation layer is not formed due to the shade of the gap was researched under conditions that the wiring 9c is formed on the surface of the substrate 10d, and the oblique evaporation of silicon oxide (SiO) is performed on the surface of the substrate 10d from a unidirectional direction S. The result of the above research is shown in FIG. 17. The oblique evaporation direction S is an orthogonal direction to the wiring 9c. 
As shown in FIG. 17, xcex94L as a width of a non-alignment-layer area where an inorganic oblique evaporation layer is not formed increases according to xcex94Z as the height of the gap without regard to the oblique evaporation angle S. Therefore, it is understood from above result that xcex94L as a width of a non-alignment-layer area where an inorganic oblique evaporation layer is not formed can be decreased by performing the oblique evaporation of inorganic material from the direction of the low gap section in the first oblique evaporation step; thus, the alignment layer can be formed as large as possible in the first oblique evaporation step, and the area which should be compensated for in the second oblique evaporation step can be lessened.
Also, in a manufacturing method for a substrate for a liquid crystal device with any construction in the present invention, of the thickness of inorganic oblique evaporation layer formed in the first oblique evaporation step should preferably be 5 nm to 16 nm, and the thickness of inorganic oblique evaporation layer formed in the second oblique evaporation step should preferably be 10 nm to 40 nm.
If the thickness of the first inorganic oblique evaporation layer is less than 5 nm, a pre-tilt angle is not provided to the liquid crystal molecules, and such a condition may cause disclination. If the thickness is larger than 16 nm, the effect which should be obtained by the second inorganic oblique evaporation layer cannot be obtained sufficiently; thus, the pre-tilt angle of liquid crystal molecules becomes larger than 20 degrees.
If the thickness of the second inorganic oblique evaporation layer is less than 10 nm, the effect that the columnar structure of this second inorganic oblique evaporation layer fills the gap of the columnar structure of inorganic material organizing the first inorganic oblique evaporation layer is insufficient; thus the pre-tilt angle of the liquid crystal molecule becomes larger than 20 degrees. If the thickness of the second inorganic oblique evaporation layer is larger than 40 nm, the gap of the columnar structure of inorganic material organizing the first inorganic oblique evaporation layer is filled; thus, the pre-tilt angle is not provided to the liquid crystal molecules, therefore there is no pre-tilt in alignment.
Also, in a manufacturing method for a substrate for a liquid crystal device with any construction in the present invention, silicon oxide can be preferably used as the above inorganic material.
A projection display device of the present invention is provided with any of the liquid crystal devices of the present invention, and a projection display device of the present invention is characterized in comprising a light source, the liquid crystal device which modulates the light emitted from the light source, and a magnifying projection optical system which magnifies the light modulated by the liquid crystal device and projects the light on a projection plane.
According to the projection display device with this construction in the present invention, by using the liquid crystal device of any of the present invention, a projection display device having high display quality with no low contrast due to inferior alignment of liquid crystals can be realized.